1. Field of the Invention
The present invention relates generally to a cover member and, in particular, to a hard cover for a pool, hot tub or the like which allows a heavy hard cover to be lifted off the top of a pool, hot tub or the like with very little effort, and to be moved to a convenient open position.
2. Background Art
With the increased use of home pools and hot tubs, there has arisen the problem of covering the pool or hot tub when it is not in use. Pool covers generally take the form of a soft cover or sheet type member positioned over the pool, or a solid "styrofoam" type floatable block member. These arrangements have disadvantages in that they are often difficult or combersome to remove and there is heat lost through the covers. In some respects, a preferable cover is in the form of a hard cover positioned entirely over the top of the pool or hot tub. However, the prior art arrangements known to the applicant have been lacking with regard to convenience of moving the cover between its closed and open positions, and also arranging the cover so that it occupies very little space in any position it assumes in moving between its closed and open positions.
A search of the U.S. patent literature has disclosed a number of prior art patents, these being as follows:
U.S. Pat. No. 4,382,312--Liggett et al shows an automobile hood hinge system that pivots the hood to the rear and holds it open at various intermediate position. When an auxiliary hinge member is released from an upper hinge bracket, the hood can be moved to various further open positions.
U.S. Pat. No. 3,844,615--Anderson shows a dumping box with a cover. The cover is positioned by a pair of pivotally mounted links. The linkage uses a hydraulic cylinder to be used to remove the cover, with the hydraulic cylinder acting through a pivoting member 40 to move the link 33.
U.S. Pat. No. 3,494,219--Hillhouse, shows a container lid which is supported in its open position by a linkage system actuated by a hydraulic cylinder. The cover is opened to a position above the container. One link is in the form of a bellcrank 34. The second link 31 is pivotally connected at a level above the lid in its closed position.
U.S. Pat. No. 2,912,237--Snyder shows a side opening door, which is supported by two pivotally mounted links. There is an additional link, connected to a motor which opens the door and rotates the door as it moves to its open position. A spring 84 prevents the crank arm 66 from from stoping at a dead center location.
U.S. Pat. No. 2,882,004--Leishman discloses a linkage system for an x-ray film holder. The linkage allows the device to rotate on two axes because of added linkage elements.
U.S. Pat. No. 2,531,140--Linde shows a trailer cover that is mounted on a spring loaded parallel linkage. The links are arranged so that the cover remains parallel to the lower section of the trailer as it moves between its open and closed position.
U.S. Pat. No. 1,923,063--Bergstron et al shows a cover that rotates on a linkage system so that it moves from the top of the container to a position behind it. There are two pivotally mounted arms which cause the cover to rotate, one of which is pivotally mounted at a back side of the structure and the other at a center location. The cover is arranged so that in its open position, substantaily all of the cover is located below the level of the upper edge of the receptacle wall.
U.S. Pat. No. 1,489,633--Evans shows a cover that rotates on pairs of arms that rotate the door ninety degrees as the door is moved between its open and closed positions.
U.S. Pat. No. 1.059,221--Saylor shows a receptacle cover that is supported by a parallel linkage the cover remains parallel to its closed position when moving to its open position.